1. Field of the Invention
The invention generally relates to a method of growing a ribbon crystal wherein a meniscus of molten semiconductive material is attached to a vertically moving seed, and more particularly to an improved method of growing a ribbon crystal wherein the brightness of strategic portions of the growth region thereof is monitored through the use of mutually spaced sensors adapted to provide an electrical output comprising intelligence for use in controling the geometry of the ribbon.
2. Description of the Prior Art
The prior art, of course, is replete with teachings of techniques for growing ribbon crystals wherein a meniscus of molten semiconductive material is grown at a rate corresponding to the rate at which the seed is lifted from the meniscus. For example, see U.S. Pat. Nos. 3,096,158; 3,124,489; 3,293,002; 3,493,770; 3,870,477 and 3,954,551. Also, it is pointed out that the instant inventor's prior application Ser. No. 677,580 filed Apr. 16, 1976, now U.S. Pat. No. 4,075,055 is believed to include teachings relating to the instant invention.
Additionally, it is known that an elongated crystal may be drawn from a melt while growth conditions are determined in response to intelligence derived from detectors employed for sensing radiation propagated from the melt. For example, see U.S. Pat. No. 3,493,770 to R. G. Dessauer et al.
However, as can be appreciated by those familiar with techniques employed in producing single crystals in long flat strips from a melt of semiconductor material, control of the geometry of the resultant ribbon normally is considered to be an art. Therefore, production of ribbon crystals and the like has been impeded due, in part, to a lack of personnel having adequate skills required in the production of uniformly configured ribbon crystals. Moreover, due also to the fact that control of the geometry of the grown ribbon crystals is considered to be an art, difficulty has been encountered in automating ribbon crystal production.
It should, therefore, be apparent that there currently exists a need for a method of growing ribbon crystals which is particularly adapted for automation, whereby the presently recognized critical need for skilled operators is relieved and manpower requirements thus are reduced.
It is, therefore, the general purpose of the instant invention to provide an improved method of growing ribbon crystals wherein the geometry of the resultant ribbon is controled through steps particularly adapted for automation.